Abstract Despite recent progress, Black Americans continue to bear the most severe burden of HIV/AIDS in the nation, and young Black men who have sex with men (YBMSM) continue to be most affected. Antiretroviral pre- exposure prophylaxis (PrEP) has been endorsed as a potentially effective part of HIV combination prevention strategies and an opportunity to reduce new infections among YBMSM. However, without significant efforts to develop age and culturally-tailored PrEP interventions for YBMSM, PrEP use may only be accessible and utilized by older, White, more affluent MSM, further exacerbating HIV disparities. Through the framework of intersectionality, the proposed research examines how various, intersectional stigmas may limit YBMSM?s ability and willingness to use PrEP. Various stigmas experienced by Black MSM (homonegativity, racism) are associated with adverse outcomes along the HIV care continuum and there is reason to believe these stigmas may also negatively affect PrEP outcomes. The proposed study aims to address the current lack of research on YBMSM?s barriers to using PrEP and gather the data necessary to inform a tailored intervention for YBMSM. The study will take place in Milwaukee, WI. In phase I, we will conduct 9 focus groups (n=72-90) with YBMSM ages 16-25 to explore YBMSM?s knowledge and perceptions of PrEP, identify individual, community and structural level factors likely to affect PrEP uptake among YBMSM, and examine YBMSM?s general healthcare utilization patterns and barriers. Additionally, we will employ a quantitative study to examine the relationship between various stigmas (racism, medical mistrust, homonegativity) and examine the effects of intersecting stigmas on knowledge and acceptance of PrEP among 300 YBMSM. We hypothesize that racism, homonegativity, and the intersection of those stigmas will predict lower knowledge of PrEP, reduced likelihood of using PrEP, and greater PrEP stigma. We also hypothesize that the relationships between various stigmas and PrEP outcomes will be moderated by resiliency and social support. In Phase II, we will use findings from Phase I and community-based participatory research methods to develop an evidence-based multi-level intervention tailored to YBMSM to be tested in a future R34. Findings from this study may not only be useful in increasing PrEP use among YBMSM, but may also be generalized to other outcomes along the care continuum. The training plan in this Mentored Research Scientist Development Award (K01) application will provide the training and research experience necessary to support Dr. Katherine Quinn?s transition to an independent HIV prevention and intervention researcher. Training includes four primary goals: build content expertise in intersectional stigma, develop mastery of complex statistical modeling for intersectionality and mixed-methods research, build expertise in intervention science, and enhance career and professional development. The training acquired by Dr. Quinn includes didactic coursework, academic conferences, manuscript preparation, independent study, grant writing workshops and other research activities.